Classification (Odd One Out) — PPSC previous year questions

Flood, fire and cyclone are all natural calamities or disasters, and an earthquake belongs to the same class. Damage and accident are consequences rather than disasters themselves, and rain is an ordinary weather event that is not a calamity in itself.

Zinc, iron and chlorine are all chemical elements. Mica is not an element; it is a silicate mineral, a compound of several elements. So mica is the odd one out.

Copper, tin and aluminium are pure metallic elements, whereas brass is an alloy of copper and zinc. Being the only mixture among elements, brass is the odd one out.

Kennel (dog), stable (horse) and cage (bird or animal) are all shelters for animals. A house is a dwelling for human beings. So 'House' is the odd one out.

Number the arrangement from the left: J(1) *(2) R(3) 3(4) P(5) L(6) 2(7) #(8) I(9) N(10) 7(11) O(12) C(13) @(14) K(15) 5(16) D(17) =(18) M(19) $(20) 6(21) B(22) <(23) A(24) Q(25) 4(26). In each group the second element is three places to the left of the first, and the third is one place to the right of the first. > 2(7) → 3(4), #(8); O(12) → I(9), C(13); K(15) → O(12), 5(16) In option (d), B(22) → $(20) is only two places to the left, so (d) does not belong.

Work-Leisure, Day-Night and Expedite-Procrastinate are pairs of opposites. 'Frequently' and 'Always' are not opposites; both mean 'often', differing only in degree, so that pair is the odd one.

In three of the numbers the sum of the first three digits equals the last digit. > 2709: 2 + 7 + 0 = 9 ✓ > 1315: 1 + 3 + 1 = 5 ✓ > 2518: 2 + 5 + 1 = 8 ✓ > 8314: 8 + 3 + 1 = 12 ≠ 4 ✗ So 8314 is different.

Three of the numbers are one more than a perfect square: 626 = 25² + 1, 962 = 31² + 1 and 1025 = 32² + 1. The number 841 = 29² is itself a perfect square, so it breaks the pattern.

In each group the first two letters are 'opposite' letters (positions adding to 27: A–Z, C–X, E–V, T–G). In CXDW, AZBY and EVFU the third letter is the next letter after the first (C→D, A→B, E→F) and the fourth is the letter before the second (X→W, Z→Y, V→U). In TGSH this is reversed: S comes before T and H comes after G.

Lungs, pharynx and bronchioles are all parts of the respiratory system, and the alveoli, the tiny air sacs in the lungs where gas exchange takes place, belong to the same system. The ribs are part of the skeleton, the oesophagus is part of the digestive tract and nephrons are the filtering units of the kidney.